SnSeS / carbon composite material, preparation method thereof and sodium ion battery

Abstract

The invention discloses a SnSeS / carbon composite material, a preparation method thereof and a sodium ion battery. The preparation method of the SnSeS / carbon composite material comprises the following steps: mixing and ball-milling tin salt, a carbon source and a solvent to obtain a precursor; performing heat treatment on the precursor in an inert atmosphere to obtain an intermediate product; and carrying out heat treatment on the intermediate product, a sulfur source and a selenium source in an inert atmosphere to obtain the SnSeS / carbon composite material. The SnSeS / carbon composite material prepared by the method has a three-dimensional carbon frame structure, SnSeS nanoparticles are distributed inside and on the surface of the three-dimensional carbon frame structure, and the SnSeS / carbon composite material has excellent rate capability and long cycle life and can be used as a sodium ion battery negative electrode material.

Description

Technical Field

[0001] The present invention relates to the field of sodium-ion batteries. Specifically, the present invention relates to a SnSeS / carbon composite material, a preparation method thereof, and a sodium-ion battery. Background Art

[0002] Sodium is abundant and inexpensive on Earth, and the future market demand for sodium-ion batteries is growing rapidly. In sodium-ion batteries, the cost of electrode materials accounts for about 70% of the total battery cost. Therefore, it is particularly important to develop electrode materials with excellent electrochemical performance. The power density and cycle life of the battery are limited by the slow reaction kinetics of the negative electrode. The development of new high-capacity negative electrode materials is of great significance for promoting the application of sodium-ion batteries.

[0003] Ternary tin-based chalcogenide (SnSeS) provides a relatively high theoretical capacity based on multiple ion storage mechanisms and an appropriate voltage platform. Its layered structure with a large interlayer spacing is conducive to the insertion of alkali metal (Li, Na, K) ions. However, due to its unsatisfactory electron / ion conductivity, serious structural degradation and volume change, SnSeS shows kinetic defects and rapid capacity decay during charge and discharge processes.

[0004] Currently, the methods for preparing chalcogenide / carbon composite materials mainly include hydrothermal method and coprecipitation method. However, these two preparation methods have harsh reaction conditions, long time consumption, large environmental pollution, and low yield. Therefore, it is necessary to explore a simple, efficient, green and environmentally friendly synthesis method to prepare electrode materials with high specific capacity. Summary of the Invention

[0005] The present invention is based on the inventor's discovery and recognition of the following facts and problems: Due to the unsatisfactory electron / ion conductivity of SnSeS, serious structural degradation and volume change, SnSeS shows kinetic defects and rapid capacity decay during charge and discharge processes. The methods for preparing chalcogenide / carbon composite materials mainly include hydrothermal method and coprecipitation method, with harsh reaction conditions, long time consumption, large environmental pollution, and low yield.

[0006] The embodiments of the present invention aim to solve at least one of the technical problems in the related art to some extent. For this reason, the embodiments of the present invention provide a SnSeS / carbon composite material, a preparation method thereof, and a sodium-ion battery. The SnSeS / carbon composite material has a three-dimensional carbon framework structure, and SnSeS nanoparticles are distributed inside and on the surface, having excellent rate performance and a long cycle life, and can be used as a negative electrode material for sodium-ion batteries.

[0007] The embodiments of the present invention provide a preparation method of a SnSeS / carbon composite material, including the following steps:

[0008] (1) Mix a tin salt, a carbon source, and a solvent by ball milling to obtain a precursor;

[0009] (2) Heat-treat the precursor under an inert atmosphere to obtain an intermediate product;

[0010] (3) Heat-treat the intermediate product with a sulfur source and a selenium source under an inert atmosphere to obtain a SnSeS / carbon composite material.

[0011] Advantages and technical effects brought by the preparation method of the SnSeS / carbon composite material in the embodiments of the present invention: Prepare a tin-based carbon composite precursor through a mechanical ball milling process, and obtain a SnSeS / carbon composite material (SnSeS / C) through heat treatment by high-temperature annealing and re-heat treatment by gas-phase selenium sulfidation. Specifically, the ball milling process is the core technical means to achieve nanocompositeization. Through the action of mechanical force, the tin salt and the carbon source are uniformly compounded at the nanoscale to form a nanocomposite material with a synergistic effect, providing a structural basis and a uniformly dispersed precursor for the formation of a three-dimensional carbon framework structure during subsequent high-temperature treatment. Ball milling promotes the uniform dispersion of the tin-based material and the carbon material, forming a nanocomposite structure and avoiding local agglomeration. Introducing a carbon source during ball milling, on the one hand, promotes the formation of a cross-linked three-dimensional carbon framework during high-temperature treatment. Nanocompositeization shortens the electron / ion transport path inside SnSeS and provides an external fast electron transport channel to accelerate the electrode reaction kinetics, providing more active sites, thereby obtaining a SnSeS / carbon composite material with excellent rate performance and a long cycle life, which is suitable for use as the anode material of a sodium-ion battery; on the other hand, it is found that adding a carbon source during ball milling can reduce the agglomeration of active particles. Heat treatment of the precursor promotes the interaction between the tin-based material and the carbon material, optimizing the crystal structure and microscopic morphology of the tin-based material. Heat treatment of the intermediate product is carried out by gas-phase selenium sulfidation to form a SnSeS phase, obtaining a SnSeS / carbon composite material.

[0012] In the embodiments of the present invention, the SnSeS / carbon composite material uses a ternary tin-based chalcogenide (SnSeS), which provides a relatively high theoretical capacity based on multiple ion storage mechanisms and an appropriate voltage platform. Its layered structure with a large interlayer spacing is conducive to the insertion and storage of alkali (Li, Na, K) ions. The method of the present invention composites nanostructured SnSeS with carbon to accelerate the electrode reaction kinetics by shortening the electron / ion transport path inside SnSeS and providing an external fast electron transport channel; the SnSeS / carbon composite material has excellent rate performance and a long cycle life and can be used as the anode material of a sodium-ion battery.

[0013] In the embodiments of the present invention, the method of the present invention is simple to operate, environmentally friendly, and has a high yield. The tin-based precursor prepared by the mechanochemical method effectively avoids the problems of long time consumption and large amount of solvents required in the synthesis of materials by the traditional co-precipitation method and hydrothermal method. The synthesis process is simple and efficient, and can be extended for production, which is suitable for large-scale industrialization.

[0014] In some embodiments, in the step (1), the tin salt includes at least one of tin oxalate, tin chloride, and tin sulfate;

[0015] and / or, the carbon source includes at least one of coconut shell charcoal, rice husk charcoal, and straw charcoal;

[0016] and / or, the molar amount of the tin salt and the mass ratio of the carbon source is (1 - 5 mmol):(1 - 5 g);

[0017] and / or, the solvent includes at least one of water, ethanol, and N,N-dimethylformamide.

[0018] In some embodiments, in the step (1), during the ball milling process, the total mass of the tin salt and the carbon source and the mass ratio of the ball milling beads is 1:(2 - 60);

[0019] and / or, the ball milling time is 1 - 20 h;

[0020] and / or, the ball milling speed is 200 - 600 rpm.

[0021] In some embodiments, in the step (2), the inert atmosphere includes at least one of nitrogen and argon;

[0022] and / or, the heat treatment temperature is 400 - 1000 °C;

[0023] and / or, the heat treatment holding time is 1 - 5 h.

[0024] In some embodiments, in the step (3), the selenium source includes at least one of selenium powder and selenium dioxide;

[0025] and / or, the sulfur source includes at least one of sulfur powder, thiourea, and thioacetamide;

[0026] and / or, the mass ratio of the intermediate product to the sulfur source and the selenium source is 1:(2 - 5):(2 - 5);

[0027] and / or, the heat treatment temperature is 300 - 600 °C;

[0028] and / or, the heat treatment holding time is 1 - 3 h;

[0029] and / or, the inert atmosphere includes at least one of nitrogen and argon.

[0030] In some embodiments, in step (3), the SnSeS / carbon composite material has a three-dimensional carbon framework structure, and SnSeS particles are distributed inside and on the surface of the three-dimensional carbon framework structure; the particle size of the SnSeS particles is 20-50 nm.

[0031] An embodiment of the present invention provides a SnSeS / carbon composite material, which is prepared by the preparation method described in the embodiment of the present invention. In the embodiment of the present invention, the SnSeS / carbon composite material has a three-dimensional carbon framework structure, and SnSeS nanoparticles are distributed inside and on the surface, and has excellent rate performance and a long cycle life.

[0032] An embodiment of the present invention provides an application of a SnSeS / carbon composite material for a sodium-ion battery. In the embodiment of the present invention, the SnSeS / carbon composite material has a three-dimensional carbon framework structure, and SnSeS nanoparticles are distributed inside and on the surface, and has excellent rate performance and a long cycle life, and can be used as a negative electrode material for a sodium-ion battery.

[0033] An embodiment of the present invention provides a negative electrode material, including the SnSeS / carbon composite material described in the embodiment of the present invention. In the embodiment of the present invention, the SnSeS / carbon composite material has a three-dimensional carbon framework structure, and SnSeS nanoparticles are distributed inside and on the surface, and has excellent rate performance and a long cycle life, and can be used as a negative electrode material.

[0034] An embodiment of the present invention provides a sodium-ion battery, including the SnSeS / carbon composite material described in the embodiment of the present invention. In the embodiment of the present invention, the SnSeS / carbon composite material has a three-dimensional carbon framework structure, and SnSeS nanoparticles are distributed inside and on the surface, and has excellent rate performance and a long cycle life, and can be used for a sodium-ion battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 are scanning electron microscope (SEM) images of SnSeS / C prepared in Example 1 at different magnifications.

[0036] Figure 2 is the X-ray diffraction (XRD) pattern of SnSeS / C prepared in Example 1.

[0037] Figure 3 is the battery cycle performance of the SnSeS / C composite material prepared in Example 1.

[0038] Figure 4 is the battery rate performance of the SnSeS / C composite material prepared in Example 1. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0039] Embodiments of the present invention will be described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present invention, and should not be construed as limiting the present invention.

[0040] A method for preparing a SnSeS / carbon composite material according to an embodiment of the present invention includes:

[0041] (1) Mixing a tin salt, a carbon source and a solvent and performing ball milling to obtain a precursor;

[0042] (2) Performing heat treatment on the precursor in an inert atmosphere to obtain an intermediate product;

[0043] (3) Performing heat treatment on the intermediate product with a sulfur source and a selenium source in an inert atmosphere to obtain a SnSeS / carbon composite material.

[0044] The method for preparing a SnSeS / carbon composite material according to an embodiment of the present invention prepares a tin-based carbon composite precursor through a mechanical ball milling process, and obtains a SnSeS / carbon composite material (SnSeS / C) through heat treatment at high temperature annealing and secondary heat treatment for gas-phase selenium sulfidation. Specifically, the ball milling process is the core technical means to achieve nanocompositeization. By the action of mechanical force, the tin salt and the carbon source are uniformly compounded at the nanoscale to form a nanocomposite material with a synergistic effect, providing a structural basis and a uniformly dispersed precursor for the formation of a three-dimensional carbon framework structure during the subsequent high-temperature treatment process. Ball milling promotes the uniform dispersion of the tin-based material and the carbon material, forms a nanocomposite structure, and avoids local agglomeration. Introducing a carbon source during ball milling, on the one hand, promotes the formation of a cross-linked three-dimensional carbon framework during the high-temperature treatment process. Nanocompositeization shortens the electron / ion transport path inside SnSeS and provides an external fast electron transport channel to accelerate the electrode reaction kinetics, providing more active sites, thereby obtaining a SnSeS / carbon composite material with excellent rate performance and a long cycle life, which is suitable for use as an anode material for sodium-ion batteries; on the other hand, it is found that adding a carbon source during the ball milling process can reduce the agglomeration of active particles. Heat treatment of the precursor promotes the interaction between the tin-based material and the carbon material, and optimizes the crystal structure and microscopic morphology of the tin-based material. Heat treatment of the intermediate product performs gas-phase selenium sulfidation to form a SnSeS phase, and a SnSeS / carbon composite material is obtained.

[0045] In the embodiments of the present invention, the SnSeS / carbon composite material uses a ternary tin-based chalcogenide (SnSeS), which provides a high theoretical capacity based on multiple ion storage mechanisms and an appropriate voltage platform. Its layered structure with a large interlayer spacing is conducive to the insertion and storage of alkali (Li, Na, K) ions. The method of the present invention composits nanostructured SnSeS with carbon, and accelerates the electrode reaction kinetics by shortening the electron / ion transport path inside SnSeS and providing an external fast electron transport channel; the SnSeS / carbon composite material has excellent rate performance and a long cycle life, and can be used as the anode material of a sodium-ion battery.

[0046] In the embodiments of the present invention, the method of the present invention is simple to operate, environmentally friendly and has a high yield. The tin-based precursor prepared by the mechanochemical method effectively avoids the problems of long production time and the need for a large amount of solvents in the traditional coprecipitation method and hydrothermal method for synthesizing materials. The synthesis process is simple and efficient, and can be extended for production, which is suitable for large-scale industrialization.

[0047] In some embodiments, in the step (1), the tin salt includes at least one of tin oxalate, tin chloride, and tin sulfate.

[0048] In some embodiments, in the step (1), the carbon source includes at least one of coconut shell charcoal, rice husk charcoal, and straw charcoal, preferably coconut shell charcoal; the carbon source can be obtained by purchase.

[0049] In the embodiments of the present invention, coconut shell charcoal has a porous three-dimensional carbon structure, with a large pore volume and specific surface area, and has chemical stability and environmental friendliness, which helps to improve the ion adsorption capacity. At the same time, the addition of coconut shell charcoal plays a positive role in the dispersion of metal salts in the ball milling medium; coconut shell charcoal is conducive to ion transport. The composite of SnSeS and coconut shell charcoal can significantly improve the conductivity and structural stability of the material. The buffering effect of coconut shell charcoal can alleviate the volume change of SnSeS during charge and discharge, reduce material pulverization, and thus improve the cycle life.

[0050] In some embodiments, in the step (1), the molar amount of the tin salt and the mass of the carbon source are in the ratio of (1 - 5 mmol):(1 - 5 g), specifically, 1 - 5 mmol (for example, 1, 2, 3, 4, 5):1 - 5 g (for example, 1, 1.5, 2, 3, 4, 5);

[0051] In specific embodiments, the molar amount of the tin salt is 1 - 5 mmol, for example, it can be 1 mmol, 2 mmol, 3 mmol, 4 mmol, 5 mmol; the mass of the carbon source is 1 - 5 g, for example, it can be 1 g, 1.5 g, 2 g, 3 g, 4 g, 5 g.

[0052] In the embodiments of the present invention, the molar amount of the tin salt and the mass ratio of the carbon source is (1-5 mmol):(1-5 g). With sufficient carbon source, the tin salt can adhere to the carbon source more effectively, thereby improving the dispersibility of the tin salt, which is beneficial to further improving the rate performance and cycling performance of the SnSeS / carbon composite material. If the total amount of the carbon source is excessive compared to the tin salt, it will completely wrap the metal salt and reduce the ball milling efficiency; if the total amount of the carbon source is too small compared to the tin salt, the dispersion degree of the carbon source in the material will be limited, resulting in an incomplete conductive network and affecting the electron transfer between the active substances.

[0053] In some embodiments, in the step (1), the solvent includes at least one of water, ethanol or N,N-dimethylformamide. Optionally, the water is deionized water; the mass-volume ratio of the carbon source and the solvent is 1-5 g:1-6 mL. Specifically, 1-5 g (for example, 1, 2, 3, 4, 5):1-6 mL (for example, 1, 2, 3, 4, 5, 6); in a specific embodiment, the amount of the solvent can be 1-6 mL, specifically, for example, 1 mL, 2 mL, 3 mL, 4 mL, 5 mL, 6 mL.

[0054] In some embodiments, in the step (1), the tin salt, the carbon source and the solvent are mixed and ball milled; optionally, during the ball milling process, the mass ratio of the total mass of the tin salt and the carbon source to the mass of the ball milling beads is 1:(2-60). Specifically, 1:2-60 (for example, 2, 3, 5, 10, 20, 30, 40, 50, 60); the ball milling time is 1-20 h, specifically, for example, 1 h, 5 h, 10 h, 15 h, 20 h; the ball milling speed is 200-600 rpm, specifically, for example, 200 rpm, 300 rpm, 400 rpm, 500 rpm, 600 rpm; the ball milling is carried out in a ball milling jar. In the embodiments of the present invention, by adjusting the ball milling time, etc., it is beneficial to further regulate the microstructure and properties of the material.

[0055] In some embodiments, in the step (2), the precursor is heat treated in an inert atmosphere to obtain an intermediate product; optionally, the inert atmosphere includes at least one of nitrogen or argon; the heat treatment temperature is 400-1000 °C, specifically, for example, 400 °C, 500 °C, 600 °C, 700 °C, 800 °C, 1000 °C; the heat treatment holding time is 1-5 h, specifically, for example, 1 h, 2 h, 3 h, 4 h, 5 h; the heat treatment heating rate is 1-3 °C / min, specifically, for example, 1 °C / min, 2 °C / min, 3 °C / min; the heat treatment is carried out in a tube furnace.

[0056] In the embodiments of the present invention, the heat treatment temperature is 400 to 1000 °C, which is beneficial to promoting the interaction and compounding of the tin-based material and the carbon material dispersed on the nanoscale, promoting the formation of a cross-linked three-dimensional carbon framework structure, and obtaining a composite of Sn metal and carbon as an intermediate product. If the temperature is too high, the structure of the material will be damaged and the performance of the material will be reduced.

[0057] In some embodiments, in step (3), the intermediate product is heat-treated with a sulfur source and a selenium source in an inert atmosphere to obtain a SnSeS / carbon composite material;

[0058] Optionally, the selenium source includes at least one of selenium powder and selenium dioxide; the sulfur source includes at least one of sulfur powder, thiourea, and thioacetamide;

[0059] Optionally, the mass ratio of the intermediate product to the sulfur source and the selenium source is 1:2 to 5:2 to 5. Specifically, it is 1:2 to 5 (for example, 2, 3, 4, 5):2 to 5 (for example, 2, 3, 4, 5);

[0060] Optionally, the heat treatment temperature is 300 to 600 °C. Specifically, for example, 300 °C, 400 °C, 500 °C, 600 °C; the heat treatment holding time is 1 to 3 h. Specifically, for example, 1 h, 2 h, 3 h; the inert atmosphere includes at least one of nitrogen or argon; the heat treatment is carried out in a tube furnace.

[0061] In the embodiments of the present invention, the intermediate product with uniformly dispersed tin-based material on the nanoscale is subjected to gas-phase selenium sulfidation by heat treatment to obtain a SnSeS / carbon composite material. The heat treatment temperature is 300 to 600 °C, which is beneficial to the moderate growth of grains inside the material and the formation of a stable crystal structure. If the temperature is too high or too low, it will cause the material structure to collapse, phase change, or excessive grain coarsening, reducing the material performance.

[0062] In some embodiments, in step (3), the SnSeS / carbon composite material has a three-dimensional carbon framework structure, and SnSeS particles are distributed inside and on the surface of the three-dimensional carbon framework structure; the SnSeS particles are uniformly distributed inside and on the surface of the three-dimensional carbon framework structure; the SnSeS particles are uniformly distributed on the surface of the SnSeS / carbon composite material; the particle size of the SnSeS particles is 20 to 50 nm. Specifically, for example, 20 nm, 30 nm, 40 nm, 50 nm.

[0063] In the embodiments of the present invention, the SnSeS / carbon composite material has a three-dimensional carbon framework structure and SnSeS particles are distributed inside and on the surface, which is beneficial to preventing agglomeration and ensuring the efficient utilization of active substances. The particle size of the SnSeS particles is 20 to 50 nm, which has higher electrochemical activity and is beneficial to improving the specific capacity and charge-discharge efficiency of the material.

[0064] A SnSeS / carbon composite material according to an embodiment of the present invention, the SnSeS / carbon composite material is prepared by the preparation method described in the embodiment of the present invention. In the embodiment of the present invention, the SnSeS / carbon composite material has a three-dimensional carbon framework structure and SnSeS nanoparticles are distributed inside and on the surface, and has excellent rate performance and a long cycle life.

[0065] An application of a SnSeS / carbon composite material according to an embodiment of the present invention, which is used for a sodium-ion battery. In the embodiment of the present invention, the SnSeS / carbon composite material has a three-dimensional carbon framework structure and SnSeS nanoparticles are distributed inside and on the surface, and has excellent rate performance and a long cycle life, and can be used as a negative electrode material for a sodium-ion battery.

[0066] In some embodiments, it is used as a negative electrode material for a sodium-ion battery.

[0067] A negative electrode material according to an embodiment of the present invention includes the SnSeS / carbon composite material described in the embodiment of the present invention. In the embodiment of the present invention, the SnSeS / carbon composite material has a three-dimensional carbon framework structure and SnSeS nanoparticles are distributed inside and on the surface, and has excellent rate performance and a long cycle life, and can be used as a negative electrode material.

[0068] A sodium-ion battery according to an embodiment of the present invention includes the SnSeS / carbon composite material described in the embodiment of the present invention. In the embodiment of the present invention, the SnSeS / carbon composite material has a three-dimensional carbon framework structure and SnSeS nanoparticles are distributed inside and on the surface, and has excellent rate performance and a long cycle life, and can be used for a sodium-ion battery.

[0069] The present invention will be described below with reference to specific embodiments. It should be noted that these embodiments are merely illustrative and do not limit the present invention in any way.

[0070] Example 1

[0071] A preparation method of a SnSeS / carbon composite material includes the following steps:

[0072] (1) Take 4 mmol of tin chloride, 1.5 g of coconut shell charcoal and 2 mL of deionized water and add them to an agate ball milling jar in sequence; add 45 g of agate ball milling beads to the agate ball milling jar; transfer the ball milling jar into a planetary ball mill and complete the assembly, and then carry out ball milling for a total duration of 5 h at a rotation speed of 400 rpm to obtain a precursor;

[0073] (2) Carry out high-temperature heat treatment on the precursor under the protection of a nitrogen atmosphere, heat it to 600 °C at a heating rate of 2 °C / min and then carry out high-temperature heat treatment for 2 h to obtain an intermediate product;

[0074] (3) The intermediate product is heat-treated at 500 °C for 2 h in a nitrogen atmosphere with sulfur powder and selenium powder in a mass ratio of 1:2:2 to obtain the SnSeS / carbon composite material (SnSeS / C).

[0075] Figure 1 (a) and (b) are SEM images of the SnSeS / carbon composite material in Example 1. It can be seen that the SnSeS / carbon composite material has a three-dimensional carbon framework structure, and SnSeS particles are evenly distributed inside and on the surface of the three-dimensional carbon framework structure.

[0076] Figure 2 It is the XRD pattern of the SnSeS / carbon composite material in Example 1. The results show that the SnSeS / carbon composite material has hexagonal tin selenosulfide (JCPDS No. 97-065-0864). The broad diffraction peak appearing near 26° belongs to amorphous carbon, and the crystallinity of the product is good, indicating that the SnSeS / carbon composite material is successfully synthesized.

[0077] Example 2

[0078] The method is the same as that in Example 1, except that in step (1), coconut shell charcoal is replaced by rice husk charcoal.

[0079] Example 3

[0080] The method is the same as that in Example 1, except that in step (1), coconut shell charcoal is replaced by straw charcoal.

[0081] Example 4

[0082] A preparation method of a SnSeS / carbon composite material includes the following steps:

[0083] (1) Take 2 mmol of tin chloride, 3 g of straw charcoal, and 2 mL of deionized water and add them to an agate ball milling jar in sequence; add 45 g of agate ball milling beads to the agate ball milling jar; transfer the ball milling jar into a planetary ball mill and complete the assembly, and then carry out ball milling for a total duration of 8 h at a rotation speed of 300 rpm to obtain a precursor;

[0084] (2) Heat-treat the precursor under the protection of a nitrogen atmosphere and heat it to 500 °C at a heating rate of 2 °C / min and then carry out high-temperature heat treatment for 3 h to obtain an intermediate product;

[0085] (3) The intermediate product is heat-treated at 300 °C for 1 h in a nitrogen atmosphere with thiourea and selenium dioxide in a mass ratio of 1:3:3 to obtain the SnSeS / carbon composite material.

[0086] Example 5

[0087] A preparation method of a SnSeS / carbon composite material includes the following steps:

[0088] (1) Add 2 mmol of tin sulfate, 3 g of rice husk carbon, and 4 mL of ethanol to an agate ball milling jar in sequence; add 30 g of agate ball milling beads to the agate ball milling jar; transfer the ball milling jar into a planetary ball mill and complete the assembly, then carry out ball milling for a total duration of 8 h at a rotation speed of 600 rpm to obtain a precursor;

[0089] (2) Carry out high-temperature heat treatment on the precursor under the protection of a nitrogen atmosphere, and heat it to 700 °C at a heating rate of 2 °C / min and then carry out high-temperature heat treatment for 1 h to obtain an intermediate product;

[0090] (3) Heat-treat the intermediate product, thioacetamide, and selenium dioxide in a mass ratio of 1:2:2 at 400 °C for 1 h under a nitrogen atmosphere to obtain a SnSeS / carbon composite material.

[0091] Example 6

[0092] A preparation method of a SnSeS / carbon composite material, comprising the following steps:

[0093] (1) Add 3 mmol of tin oxalate, 6 g of rice husk carbon, and 2 mL of N,N-dimethylformamide to an agate ball milling jar in sequence; add 20 g of agate ball milling beads to the agate ball milling jar; transfer the ball milling jar into a planetary ball mill and complete the assembly, then carry out ball milling for a total duration of 6 h at a rotation speed of 500 rpm to obtain a precursor;

[0094] (2) Carry out high-temperature heat treatment on the precursor under the protection of a nitrogen atmosphere, and heat it to 600 °C at a heating rate of 2 °C / min and then carry out high-temperature heat treatment for 3 h to obtain an intermediate product;

[0095] (3) Heat-treat the intermediate product, thiourea, and selenium powder in a mass ratio of 1:5:5 at 500 °C for 1 h under a nitrogen atmosphere to obtain a SnSeS / carbon composite material.

[0096] Comparative Example 1

[0097] The preparation method is the same as that of Example 1, except that in step (3), sulfur powder is not added.

[0098] Comparative Example 2

[0099] The preparation method is the same as that of Example 1, except that in step (3), selenium powder is not added.

[0100] Comparative Example 3

[0101] A preparation method of a SnSeS / carbon composite material, comprising the following steps:

[0102] (1) 4 mmol of tin chloride, sulfur powder, selenium powder, 1.5 g of coconut shell carbon and 2 mL of deionized water were successively added into an agate ball milling jar. Among them, the dosages of sulfur powder and selenium powder were the same as those in Example 1 respectively. 45 g of agate ball milling beads were added into the agate ball milling jar. The ball milling jar was transferred into a planetary ball mill and assembled, and then ball milling was carried out for a total duration of 5 h at a rotation speed of 400 rpm to obtain a precursor.

[0103] (2) The precursor was subjected to high-temperature heat treatment under the protection of a nitrogen atmosphere. It was heated to 600 °C at a heating rate of 2 °C / min and then heat-treated at a high temperature for 2 h to obtain the SnSeS / carbon composite material.

[0104] Comparative Example 4

[0105] The preparation method was the same as that of Example 1, except that in step (1), 6 mmol of tin chloride and 1 g of coconut shell carbon were used.

[0106] Comparative Example 5

[0107] The preparation method was the same as that of Example 1, except that in step (1), 1 mmol of tin chloride and 6 g of coconut shell carbon were used.

[0108] Performance test

[0109] The materials obtained in the examples or comparative examples were respectively mixed and ground with a conductive agent (Super P) and a binder (polyvinylidene fluoride) according to a mass ratio of 7:2:1, and then an appropriate amount of N-methylpyrrolidone was added to make a homogeneous slurry. Then, the above slurry was evenly coated on a current collector (copper foil) with a coater, dried at a constant temperature of 80 °C for 12 h, and then punched into a pole piece with a diameter of 12 mm. Glass fiber was used as the separator and a sodium sheet was used as the counter electrode. 1.0 mol / L NaPF6 dissolved in diethylene glycol dimethyl ether was used as the electrolyte, and a CR2025 type button battery was assembled in a glove box filled with an argon atmosphere and with a water oxygen value less than 0.01 ppm. After standing at a constant temperature of 25 °C for 24 h, a Neware tester was used to perform a constant current charge-discharge test in the range of 0.01 - 3 V.

[0110] Figure 3 It is the cycle performance diagram of the sodium ion battery of the SnSeS / C composite material prepared in Example 1. At a current density of 1 A / g, the discharge specific capacity reaches 533 mAh / g after cycling 200 times, and the SnSeS / carbon composite material has a long cycle life.

[0111] Figure 4The rate performance graph of the sodium-ion battery using the SnSeS / C composite material prepared in Example 1. At current densities of 0.1 A / g, 0.2 A / g, 0.5 A / g, 1 A / g, 2 A / g, and 5 A / g, the reversible specific capacities are 652 mAh / g, 656 mAh / g, 648 mAh / g, 620 mAh / g, 573 mAh / g, and 522 mAh / g respectively. The SnSeS / carbon composite material exhibits excellent rate performance.

[0112] The rate discharge specific capacities of the examples or comparative examples are shown in Table 1.

[0113] Table 1

[0114]

[0115] As can be seen from Table 1, the SnSeS / carbon composite materials prepared by the present invention in Examples 1-6, as the negative electrode materials for sodium-ion batteries, have excellent rate performance and long cycle life.

[0116] Comparing Examples 1-3, when the carbon source was changed in Examples 2 and 3, the performance of the material at currents from 0.1 A / g to 1 A / g was lower than that of Example 1. This is because coconut shell charcoal was used in Example 1, which has a large pore volume and specific surface area, helping to improve ion adsorption capacity. At the same time, the addition of coconut shell charcoal played a positive role in the dispersion of metal salts in the ball milling medium. When the carbon source is sufficient, the metal salts can adhere to the carbon source more effectively, thereby improving their dispersion in the medium, and further improving the dispersion of SnSeS and the rate performance.

[0117] Comparing Example 1 with Comparative Example 1 and Comparative Example 2, it can be found that when the sulfur source or selenium source is not added, the rate performance of the material decreases. The SnSeS / carbon composite material in Example 1 has excellent rate performance and long cycle life.

[0118] Comparing Example 1 with Comparative Example 3, it can be found that in Comparative Example 3, all raw materials were mixed, ball milled, and heat-treated in one step, and the rate performance of the material decreased. This is because when tin chloride, sulfur powder, selenium powder, and coconut shell charcoal were mixed and heat-treated together, the dispersion of SnSeS was relatively poor. In Example 1, the tin salt and carbon source were first uniformly compounded at the nanoscale by ball milling, and the precursor heat treatment promoted the interaction between the tin-based material and the carbon material, optimizing the crystal structure and microstructure of the tin-based material. The intermediate product heat treatment was carried out for gas-phase selenium sulfidation to form the SnSeS phase, obtaining the SnSeS / carbon composite material, improving the dispersion of SnSeS and the rate performance.

[0119] Comparing Example 1 and Comparative Example 4, it can be found that when the dosage of tin salt in Comparative Example 4 is too high, the dispersion degree of the carbon source in the material will be limited, resulting in an incomplete conductive network, affecting the transport of electrons between active substances, and reducing the rate performance.

[0120] Comparing Example 1 and Comparative Example 5, it can be found that too much carbon source will wrap the metal salt, preventing the contact and reaction between metal salts, which may cause changes in the structure and properties of the material, and thus have an adverse effect on the battery performance.

[0121] In the present invention, the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0122] Although the above embodiments have been shown and described, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Any changes, modifications, substitutions, and variations made by those of ordinary skill in the art to the above embodiments are within the protection scope of the present invention.

Claims

1. A preparation method of SnSeS / carbon composite material, characterized in that, It includes the following steps: (1) Mix stannous salt, carbon source and solvent and carry out ball milling to obtain a precursor; (2) Heat-treat the precursor under an inert atmosphere to obtain an intermediate product; (3) Heat-treat the intermediate product with a sulfur source and a selenium source under an inert atmosphere to obtain a SnSeS / carbon composite material.

2. The preparation method of the SnSeS / carbon composite material according to claim 1, characterized in that, In the step (1), the stannous salt includes at least one of stannous oxalate, stannous chloride, and stannous sulfate; and / or, the carbon source includes at least one of coconut shell charcoal, rice husk charcoal, and straw charcoal; and / or, the molar amount ratio of the stannous salt to the mass of the carbon source is (1-5 mmol):(1-5 g); and / or, the solvent includes at least one of water, ethanol, and N,N-dimethylformamide.

3. The preparation method of the SnSeS / carbon composite material according to claim 1, characterized in that, In the step (1), during the ball milling process, the mass ratio of the total mass of the stannous salt and the carbon source to the mass of the ball milling beads is 1:(2-60); and / or, the ball milling time is 1-20 h; and / or, the ball milling rotation speed is 200-600 rpm.

4. The preparation method of the SnSeS / carbon composite material according to claim 1, characterized in that, In the step (2), the inert atmosphere includes at least one of nitrogen or argon; and / or, the heat treatment temperature is 400-1000 °C; and / or, the heat treatment holding time is 1-5 h.

5. The preparation method of the SnSeS / carbon composite material according to claim 1, wherein In the step (3), the selenium source includes at least one of selenium powder and selenium dioxide; and / or, the sulfur source includes at least one of sulfur powder, thiourea, and thioacetamide; and / or, the mass ratio of the intermediate product to the sulfur source and the selenium source is 1:(2-5):(2-5); and / or, the heat treatment temperature is 300-600 °C; and / or, the heat treatment holding time is 1-3 h; and / or, the inert atmosphere includes at least one of nitrogen or argon.

6. The preparation method of the SnSeS / carbon composite material according to claim 1, characterized in that, In the step (3), the SnSeS / carbon composite material has a three-dimensional carbon framework structure, and SnSeS particles are distributed inside and on the surface of the three-dimensional carbon framework structure; the particle size of the SnSeS particles is 20-50 nm.

7. A SnSeS / carbon composite material, characterized in that, The SnSeS / carbon composite material is prepared by the preparation method according to any one of claims 1-6.

8. Use of the SnSeS / carbon composite material according to claim 7, characterized in that, It is used for sodium ion batteries.

9. A negative electrode material, characterized in that, It includes the SnSeS / carbon composite material according to claim 7.

10. A sodium-ion battery, characterized in that, It includes the SnSeS / carbon composite material according to claim 7.

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